The present invention relates a friction welding method and an apparatus for carrying out this method.
Methods and apparatus for attaching two elements together by friction welding are well-known in the art and a typical example is illustrated in French Patent 2,641,222. This particular example describes a method for fabricating welded parts having an accurate and reproducible final length.
Pressure-welding procedures involving inter-metal diffusion and transition into the super-plastic state are known and a typical example is disclosed in French Patent 2,299,940. In this disclosure, the welding zone of the metal parts being welded together is subjected to an alternating, and repeating heating and cooling cycle.
While the known friction-welding techniques have been generally successful, many quality problems remain, in particular when such techniques are used in making aeronautical engine parts of precipitation-hardened nickel superalloys. Unacceptable mechanical characteristics have been observed in some of these parts due to the crack propagation properties caused by certain metallurgical changes in the welded zones after insufficiently controlled inertial friction welding, particularly where thermal cycling has taken place in the welding zones.